Coated laminated structural material



106. cowosmows, Examiner comma 0R PLASTIC 5S Referenke Nov. 28, 1939. E, c, H HE 2,181,811

COATED LAMINATED STRUCTURAL MATERIAL Filed May 19, 1937 IN VENTOR.

ATTORNEYS,

Jot m Patented Nov. 28, 1939 UNITED STATES PATENT OFFICE COATED LALI'INATED STRUCTURAL MATERIAL Everett C. Hughes, Cleveland, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, a

corporation of Ohio Application May 19,

11 Claims.

This invention relates to laminated materials, and it is among the objects of the invention to provide a material which although including sheeted cellulose is capable of withstanding considerable mechanical stress, and also affording a barrier to moisture and oil. Other objects and advantages will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described, and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail certain illustrative embodiments of the invention, these being indicative however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawing:

The sole figure is a broken perspective, partly in section, illustrating an embodiment of the invention.

Many efforts have been made to produce a laminated cellulose structure capable of containing oils. The problem has offered difficulties not apparent at first, and many unexpected conditions have been encountered by materials along this line which have been undertaken. Structures dependent upon coated cellulose sheets in which a heat-treated lacquer or enamel material has been supplied on the cellulose material for instance, are too expensive, and are not in all cases dependable for application in containers for liquids such as petroleum oils and greases. Efiorts employing glue as a component or employing water glass have developed an unexpected tendency to allow seepage of oil through, notwithstanding an initially apparently efiective coating upon the cellulose. I have found where a water-borne agent such as water glass is employed, there is an uneven expansion of the cellulose to which the water glass is applied, the fibrous structure tending to expand difierentially with respect to the lay of the fibre, and again in the drying out there is a differential contraction, all tending to defeat maintenance of an unbroken coating. On account of the extremely high capillary action of petroleum oil, the merest fissure in such a coated surface makes possible a progressive and ultimate seepage of the oil into the cellulose body, thus defeating the attainment of the desired end. Again, I have found that in the application of liquid coatings as employed with the object of obtaining an oil-proof cellulose structure, there is a generally unnoticed tendency for minute air bubbles to be entrapped 1937, Serial No. 143,542

(or 91-68) /J I in the coating surface, and these bubbles eventuate into minute penetrating pin holes which allow progressive and ultimate oil seepage. I have found however, that materials may be combined, having surface-afiinity not heretofore had, such 5 as to attain a structure whose layers are protected against infiltration of oil, irrespective of conditions encountered in storage.

The cellulose may be of character as desired in any given instance, available cheap grades of stock such as chip board, chestnut board, being adaptable for inexpensive products, and stocks such as kraft, or higher grades of stock, such as rag stock, etc., also are applicable, and one or more layers of the cellulose may be concerned, 15 associated with the water glass layer as more particularly detailed hereinafter. Thus, a layer or more designated 2 in the drawing may have a surface layer 8 of oil-resistant character and amorphous as contrasted with the fibre cellulose, this involving the modified sodium silicate therein referred to, which has aTHi'ghsurface-amnity for the cellulose, conforming accurately thereto, as applied in liquid condition, such as to eliminate occlusion of minute bubbles. After the structure is initially dried out, uneven stresses are absent, and the colloidal layer maintains its union with the fibres, without fissures, and elasticity persists such as to inhibit fissure-development which would otherwise be inherent with water glass through agents.

For the amorphous oil-proofing layer material, I incorporate with sodium silicate of quite high gravity, for instance o specific gravity, gum arabic and glycerol, and a soap. The concentration of the glycerol may'fir'ir somewhat, but if its concentration is less than 1.26 for instance water is to such extent being introduced and its total amount should not exceed certain general limits. Since water is necessary to dis- 40 solve the gum arabic, commercial sodium silicate having gravity of 1.42 to 1.45 is used, the amount of water which can be brought in with the glycerine is correspondingly less. Glycerine of not less than 1.26 gravity is desirable. Thus, with sodium silicate in the amount of 65-88 per cent, there may be incorporated 8-33 per cent of glycerol, and up to 6 per cent gum arabic. For the soap, I include preferably liquid soap in small amount, as tassium oleate. or a soflium soap of oleic and other fatty acids yielding a liq'fild soap, and the amount of liquid soap employed may be 0.1 to 0.3 per cent. Optionally, and with particular advantage in some instances, I also include a colloidal metallic soap such as I06. composmnws,

COATING UR PLASTIC ear h metal or aluminum. Such metal soap may be introduced into the mixture in very finely divided powder form, and be well mixed with the sodium silicate and glycerol. With particular advantage, the gum arabic instead of being incorporated directly as such, may be first made up with water to a suitable solution concentration, conveniently for instance 45 per cent, and appropriate amounts thereof may be mixed into the sodium silicate, glycerol, etc. In some instances, an equivalent for a part or all of the glycerol is such a substitute as ethylene glycol. For instance, I may employ per cent by weight of sodium silicate with SiO22Na2O ratio 3.25:1, and 21.4 per cent by weig 0 g ycero of 1.2 specific gravity, these being mixed with 5.18 per cent by weight of a 45 per cent gum arabi solution, and 0.13 per cent of liquid soap. Metallic soaps such as calcium stearate in amount of 1 per cent may be a e esired. In general such metallic soap may range from 0 to about 4 per cent. Optionally, dextrine may be incorporated with the sodium silicate, glycerol, etc, and amounts thereof may be 0.35-1.5 per cent where employed. The material applied to the cellulose, after being dried forms a surface layer of amorphous, firm, adherent character. Drying may be carried on at atmospheric temperature, or at elevated temperature preferably, as for instance to F. Not only may an oil-resistant surface be thus provided, but where laying together plies of cellulose the modified sodium silicate material may be employed as the adhesive therebetween. By laying the cellulose layers in the form of a hollow container or a tube which may be cut up into container lengths, and supplying the inner surface of the oil-resistant material as noted, convenient forms of structure for applicable usage may be had. Advantageously thus, the oil-resistant material may be employed as the adhesive for all of the plies of the tubing, wound spirally or convolutely, and as a lap glue on an inner ply. Inner and outer surfaces of the tubular container may be supplied with the oil proof layer as exposed surface, or the inside may be so treated alone, leaving the outside to receive any other desired finishing layer. The ends of such tubular containers can be closed by sheet metal heads crimped into place on the cellulose, the amorphous layer particularly favoring a tight closure therewith. Or, especially for uses in units of not large size, I may close the ends of the tubular units with headers of laminated cellulose and amorphous oil proofing material as described. A particularly effective sealing of the heads (cellulosic or metallic) of the packages may be had em ploying the liquid material above-described or preferably of a thicker glue-like consistency, as by containing a quite high percentage of gum arabic to advantage, not however exceeding the total of 6 per cent, or especially by containing the metallic soap as a thickening and toughening component.

Instead of employing the 3.25:1 ratio sodium silicate as above-instanced, a slower setting material especially desirable for ends may be typically as follows: 86.4 per cent by weight of o di im s ili c ate of 2: 1 IatLSiQgLN820), 8.15 per cent by weight of glycerol, 3.47 pe'r cent by weight of a 45 per cmfum arabic solution, 0.13 per cent of liquid soap. Calcium stearate, finely powdered, irram'ount of about 1.92 per cent may be also incorporated.

I have found that it is of particular advantage stearate or palmitate of calcium or similar alkalin to employ sodium silicate having an SiOaINBaO ratio of specially controlled charactems s a surprisingly important bearing on the ultimate durability of the oil proof layer in usage in contact with oils and greases. I control the ratio between the limits preferably of 2.58 to 3.16 to 1. As a matter of convenience, this may e accomplished by suitable compounding of standard 2:1 sodium silicate and 3.25:1 sodium silicate stocks. Thus, 0 40 parts by weight 0 the 231mm silicate may be mixed with 70-35 parts by weight of the 3.25:1 silicate stock. With such adjusted SiOzINazO ratio sodium silicate, the glycerol, gum arabic and alkali metal soap and other metallic soap may be incorporated, as above-described, and the material be associated with the cellulose.

This application is a continuation, in part and as to common subject matter, of my application Ser. No. 10,685, filed March 12, 1935.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

1 therefore particularly point out and distinctly claim as my invention:

1. A laminated structure, comprising plural fibrous layers of sheet cellulose, and conforming accurately to the cellulose and having substantially the same rate of expansion and contraction, an oil-proof amorphoussurface layer of sodium silicate whose SiO2:Na2O ratio is such as resultant from five to forty per cent of a 2:1 sodium silicate, and seventy to thirty-five per cent of a 3.25:1 sodium silicate, and smaller amounts of gum arabic, glyceral and soap.

2. A laminated structure, comprising plural fibrous layers of sheet cellulose, and conforming accurately to the cellulose and having substantially the same rate of expansion and contraction, an oil-proof surface layer and inter-layers of sodium silicate whose SiOzzNazO ratio is such as resultant from five to forty per cent of a 2:1 sodium silicate, and seven to thirty-five per cent of a 3.25:1 sodium silicate, and smaller amounts of gum arabic, glycerol and soap.

3. A laminated structure, comprising plural fibrous layers of sheet cellulose, and conforming accurately to the cellulose and having substantially the same rate of expansion and contraction, an ofi-proof amorphous surface layer of sodium silicate and smaller amounts of gum arabic, glycerol, and soap including a liquid soap and a colloidal metallic soap.

4. A laminated container structure, comprising plural fibrous layers of sheet cellulose, and conforming accurately to the cellulose and having substantially the same rate of expansion and contraction, an oil-proof amorphous surface layer and interspersed layers of water glass with minor amounts of glycerol, gum arabic and soap including liquid soap and a colloidal metallic soap.

5. A container structure, comprising a fibrous layer of sheet cellulose, and conforming accurately to the cellulose and having substantially the same rate of expansion and contraction, an oil-proof amorphous surface layer of sodium silicate softened by smaller amounts of glycerol, gum arabic, and a fractional percent of a liquid soap.

6. A laminated structure, comprising plural fibrous layers of sheeted cellulose, and conforming accurately to the cellulose and having substantially the same rate of expansion and contraction,

Examine:

an oil-proof amorphous surface layer of sodium silicate, and smaller amounts of gum arabic, dextrine, glycerol and soap.

7. A laminated container structure, comprising plural fibrous layers of sheeted cellulose, and conforming accurately to the cellulose and having substantially the same rate of expansion and contraction, an oil-proof amorphous surface layer consisting of water glass, an alkali metal carbonate, gum arabic, dextrine, glycerol and soap.

8. A container structure, comprising a fibrous layer of sheeted cellulose, and conforming accurately to the cellulose and having substantially the same rate of expansion and contraction, an oil-proof amorphous surface layer of sodium silicate softened by smaller amounts of gum arable. glycerol, dextrine and a fractional per cent of 9. In a laminated structure, a layer of cellulose and an oil-resistant layer thereon of controlled SiOziNarO ratio between the limits of 2.58 and 3.16 to 1 and modified by gum arable, glycerol and a small amount of a soap.

10. Sheet cellulose with adherent sodium silicate containing gum arabic and not over 0.3 per cent of a soap of an alkali metal and 1-4 per cent of a fatty acid colloidal soap of a metal from the class consisting of alkalin earth metals and aluminum.

11. Sheet cellulose with adherent sodium silicate containing gum arabic and a small amount of a soap of an alkali metal and a larger amount of a fatty acid soap of a metal from the class consisting of alkalin earth metals and aluminum.

EVERETT C. HUGHES. 

